Devices, systems, and methods for material fixation

ABSTRACT

A material fixation system is particularly adapted to improve the tendon-to-bone fixation of hamstring autografts, as well as other soft tissue ACL reconstruction techniques. The system is easy to use, requires no additional accessories, uses only a single drill hole, and can be implanted by one person. Additionally, it replicates the native ACL by compressing the tendons against the aperture of the tibial tunnel, which leads to a shorter graft and increased graft stiffness. It is adapted to accommodate single or double tendon bundle autografts or allografts. It also provides pull out strength measured to be greater than 1000 N.

This application claims the benefit under 35 U.S.C. 119(e) of the filingdate of Provisional U.S. Application Ser. No. 60/784,422, entitledMethod and Apparatus for Attaching Soft Tissues to Bone, filed on Mar.20, 2006, and of the filing date of Provisional U.S. Application Ser.No. 60/854,178, entitled Methods and Systems for Material Fixation,filed on Oct. 24, 2006, and of the filing date of Provisional U.S.Application Ser. No. 60/898,946, entitled Devices, Systems and Methodsfor Material Fixation, filed on Jan. 31, 2007. All of these priorprovisional applications are expressly incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to devices, systems and methodsfor material fixation. More specifically, the present invention relatesto a soft tissue or bone-to-bone fixation system that permits apractitioner to repair many soft tissue injuries, such as an AnteriorCruciate Ligament (ACL) injury.

One of the most common needs in orthopedic surgery is the fixation oftendon to bone. The fixation of diseased tendons into a modifiedposition is called tenodesis and is commonly required in patients withinjury to the long head of the biceps tendon in the shoulder. Inaddition, tendons which are torn from their insertion site into bonealso frequently require repair. This includes distal biceps tendontears, rotator cuff tears, and torn flexor tendons in the hand. Tendonsare also frequently used in the reconstruction of unstable joints.Common examples include anterior cruciate ligament and collateralligament reconstructions of the knee, medial and lateral elbowcollateral ligament reconstructions, ankle collateral ligamentreconstruction, finger and hand collateral ligament reconstructions andthe like.

Traditional techniques that are used to fix tendon to bone suffer from anumber of limitations as a result of the methodology used, including theuse of a “keyhole” tenodesis, pull-out sutures, bone tunnels, andinterference screw fixation. The “keyhole” tenodesis requires thecreation of a bone tunnel in the shape of a keyhole, which allows aknotted tendon to be inserted into the upper portion, and subsequentlywedged into the lower narrower portion of the tunnel where inherenttraction on the tendon holds it in place. This technique is challengingas it is often difficult to sculpt the keyhole site and insert thetendon into the tunnel. In addition, if the tendon knot unravels in thepostoperative period, the tendon will slide out of the keyhole, losingfixation.

Another traditional form of tendon fixation is the use of the “pull-outstitch.” With this technique, sutures attached to the tendon end arepassed through bone tunnels and tied over a post or button on theopposite side of the joint. This technique has lost favor in recentyears due to a host of associated complications, which include woundproblems, weak fixation strength, and potential injury to adjacentstructures.

The most common method of fixation of tendon to bone is the use of bonetunnels with either suture fixation, or interference screw fixation. Thecreation of bone tunnels is relatively complicated, often requiring anextensive exposure to identify the margins of the tunnels. Drill holesplaced at right angles are connected using small curettes. This tediousprocess is time-consuming and fraught with complications, which includepoor tunnel placement and fracture of the overlying bone bridge. Graftisometry, which is easy to determine with single point fixation, isdifficult to achieve because the tendon exits the bone from two points.After creation of tunnels, sutures must be passed through the tunnels tofacilitate the passage of the tendon graft. Tunnels should be smallenough to allow good tendon-bone contact, yet large enough to allow forgraft passage without compromising the tendon. This portion of theprocedure is often time-consuming and frustrating to a surgeon. Finally,the procedure can be compromised if the bone bridge above the tunnelbreaks, resulting in loss of fixation. The technique restricts fixationto the strength of the sutures, and does not provide any direct tendonto bone compression.

More recent advances in the field of tendon fixation involve the use ofan internally deployed toggle button, for example, the ENDOBUTTON, andthe use of interference screws to provide fixation. The ENDOBUTTONallows the fixation of tendon into a bone tunnel by creating aninternally deployed post against a bony wall. While this techniqueeliminates the need for secondary incisions to place the post, thefixation strength is limited to suture strength alone. This techniquedoes not provide direct tendon to bone compression; as such thistechnique may slow healing and lead to graft tunnel widening due to the“bungee effect” and “windshield wiper effect”. As a result, thistechnique has limited clinical applications and is used primarily forsalvage when bone tunnels break or backup fixation is important.

The use of the interference screw is the most notable advance in thefixation of tendon to bone. The screw is inserted adjacent to a tendonin a bone tunnel, providing axial compression between the screw threadsand the bony wall. Advantages include acceptable pull-out strength andrelative ease of use. Aperture fixation, the ability to fix the tendonto bone at its entrance site, is a valuable adjunct to this technique asit minimizes graft motion and subsequent tunnel widening. Somedisadvantages related to soft tissue interference screws are that theycan be difficult to use, and can also cut or compromise the tendonduring implantation.

The newest generation interference screw allows the ability to providetendon to bone fixation with limited exposure. For example, theBIO-TENODESIS SCREW (Arthrex, Inc.) allows the tensioning and insertionof tendon into bone, followed by insertion of an adjacent soft tissueinterference screw. While this screw system provides advantages in theinsertion of tendon into bone in cases when a pull through stitch is notavailable, it is still limited by the potential for tendon rotation ordisruption as the screw compresses the tendon. The surgical technique isalso complicated, typically requiring two or more hands for insertion,making it difficult to use the system without assistance duringarthroscopic or open procedures. Finally, the use of the screw requirespreparation of the tendon end, which can be difficult, time consuming,and can also require conversion of an arthroscopic procedure to open.

Focusing particularly on the ACL, current ACL repairs utilizing softtissue for the replacement graft are either difficult to perform or theyresult in less than favorable outcomes due to their relatively lowtendon-to-bone fixation. Existing ACL reconstruction techniques thathave acceptable outcomes (high tendon-to-bone fixation) involve extraoperating room time and surgeon effort due to the requirement ofmultiple drill holes, external guides and fixtures for the drill holes,and multiple assistants. Moreover, these approaches to not closelyreplicate the native ACL in its anatomy or physiology.

Two important factors in replicating the native ACL are aperturecompression and tendon length. Compressing the tendons at the apertureof the femoral tunnel will improve the healing process by increasing theintimate contact between the tendon and the bone. A study shows thatwithout intimate contact between the tendon and the bone, the result isa graft having less well organized fibrous tissue and lower pull-outstrength. The stiffness of the repair is also important to replicate thenative ACL. Graft stiffness is decreased by the length of tendon betweenthe fixation points.

Currently, two different sources are utilized for the tissue thatreplaces the injured native ACL. When the new tissue comes from thepatient's own body, the new graft is referred to as an “autograft”, andwhen cadaveric tissue is used, the new graft is referred to as an“allograft”. The most common autograft ACL reconstruction performedcurrently is the bone-patellar-tendon-bone (BTB) graft. The BTB graftwith an interference screw is used more often because it more accuratelyreplicates the native ACL due to its aperture compression at the tibialtunnel aperture. However, BTB reconstructions result in an increasedrate of anterior knee pain post-surgically for periods of up to threeyears after the reconstruction. Additionally, the harvest procedure forthe BTB autograft is invasive and can be difficult to perform.Alternatively, the hamstring tendon autograft ACL reconstructiontechnique does not result in any significant post-surgical pain, and theharvest procedure is not minimally invasive. The reason that thehamstring tendon autograft procedure is not more frequently used in ACLreconstructions is that the fixation of the hamstring tendons to thefemur an tibia, using prior art techniques, is not as strong as thefixation of the BTB autografts.

Many systems have addressed some of the problems associated with ACLreconstruction using hamstring tendons, but there is not any systemwhich addresses them all. The TriTis® system available from Scandiusattempts to more accurately replicate the native ACL by adding materialto take up space in the tibial tunnel, resulting in more intimatecontact between the tendon and the bone. However, to insert the deviceinto the femoral tunnel, the cross sectional area must be less than thecross sectional area of the hole. There is no real compression of tendonto bone. The TriTis system also requires additional drill holes,accessories, and people to perform the procedure.

The IntraFix® system available from Mitek attempts to more accuratelyreplicate the native ACL by using a screw to spread apart an integralfour quadrant sheath. This acts to compress the four tendon strandsagainst the bone. The system is easier to use than other alternatives,and does not need additional drill holes. However, it does requireadditional accessories, additional people to perform the procedure, andthe four quadrant design does not accommodate certain allografts withtwo tendon strands, such as the tibialis.

The WasherLoc™ system, available from Arthrotek, gives increasedstrength, compared to other prior art systems, but does not accuratelyreplicate the native ACL. The tendons are sized to the hole, but notcompressed to the walls. There is also a greater distance betweenfixation points with this system, which can decrease the stiffness ofthe repair.

Interference screws such as the RCI™ Screw available from Smith & Nepheware easy to use and provide compression of tendon to bone at the tibialtunnel aperture. However, the pull out strength and stiffness of therepair are significantly lower than is the case for other prior artsystems.

Thus, although there are many conventional techniques used for thefixation of tendon to bone, each having some advantages, thedisadvantages of each such technique presents a need in the art for asimple and universal technique to fixate tendon to bone such that thedevice is easy to use, the process is simple to follow, and the resultis a firm and secure tendon to bone fixation with minimal negativeeffect on the tendon. Further, such device should be easy tomanufacture, universally applied to different tendon to bone sites, andrequire minimal effort to understand and use in practice.

SUMMARY OF THE INVENTION

The present invention is a system which is particularly adapted toimprove the tendon-to-bone fixation of hamstring autografts, as well asother soft tissue ACL reconstruction techniques. The system is easy touse, requires no additional accessories, uses only a single drill hole,and can be implanted by one person. Additionally, it replicates thenative ACL by compressing the tendons against the aperture of the tibialtunnel, which leads to a shorter graft and increased graft stiffness. Itis adapted to accommodate single or double tendon bundle autografts orallografts. It also provides pull out strength measured to be greaterthan 1000 N, which is equivalent to or substantially higher than any ofthe high strength implants currently available on the market.

More particularly, a material fixation system is provided, whichcomprises two sheath portions defining a space therebetween, and a hingefor attaching the sheath portions together along one side thereof. Aninsertion member, preferably a tapered screw, is insertable into thespace for expanding the sheath portions laterally outwardly in order tourge a soft tissue graft against an adjacent bone surface. In apreferred embodiment, the hinge comprises a hinge protrusion disposed ona first of the sheath portions and a hinge slot disposed on a second ofthe sheath portions, wherein the hinge protrusion and the hinge slotengage one another. A second hinge protrusion is disposed on the secondsheath portion and a second hinge slot is disposed on the first sheathportion, wherein the second hinge protrusion and the second hinge slotalso engage one another.

A driver is utilised for engaging and moving the insertion member. A hexopening is provided in the proximal end of the insertion member forengaging a distal end of the driver.

Preferably, the screw has a bullnose screw head, and the two sheathportions are mirror images of one another.

The invention is particularly advantageous, in that the system isadapted for use whether the soft tissue graft comprises an autograft, oran allograft. A distal end of the screw comprises a cut-out portionwhich permits the distal end of the screw to easily fit between the twosheath portions, thus permitting an operator to easily start rotation ofthe screw. The screw comprises external threads and the sheath portionscomprise complementary internal threads. The screw further comprises athread start to enable easier engagement of the screw threads and thesheath threads.

At least one retaining rib is preferably disposed on at least one of thesheath portions. The rib protrudes outwardly to provide a small area ofhigher force between the sheath portion and the soft tissue graft. Thesheath portions and the insertion member are preferably adapted forinsertion into a bone tunnel in a patient's tibia, and the soft tissuegraft comprises a tendon graft for making an ACL repair. A cortical hookis preferably disposed on one of the sheath portions for engaging hardcortical bone at the procedural site.

One of the sheath halves preferably comprises a snap post and the otherone of the sheath halves preferably comprises a complementary snap hole,wherein the snap post and the snap hole are engageable with one anotherto keep the two sheath halves from opening prematurely. In the preferredembodiment, a ramp is formed on one of the sheath portions for allowinga tip of the sheath portion to provide compression between the softtissue graft and the bone at the aperture of bone tunnel in which thesystem is disposed. Flex grooves are disposed on one of the sheathportions, for permitting the sheath portion to flex and form around atip of the insertion member. A bullnose sheath tip is provided on one ofthe sheath portions.

In some embodiments, it is advantageous for the sheath portions tofurther comprise a loop for retaining a soft tissue graft along alaterally outer surface of the sheath portion.

In another aspect of the invention, there is provided an implant systemfor promoting soft tissue to bone contact in order to promote goodfixation of soft tissue to bone when making an orthopedic repair of ajoint, wherein the implant system comprises a first implant adapted forreceiving a tissue graft thereon and then being disposed in a first bonetunnel location, wherein ends of the tissue graft extend through a bonetunnel and out of a proximal end of the tunnel. A second implant isadapted for disposition in a second bone tunnel location, proximal tothe first bone tunnel location, wherein the second implant comprises aplurality of sheaths having laterally outer surfaces and being adaptedfor advancing to the first bone tunnel location by sliding over the endsof the tissue graft, so that when the second implant is in the secondbone tunnel location, the tissue grafts are disposed between thelaterally outer surfaces of the plurality of sheaths and the bonedefining the bone tunnel. An insertion member is insertable between theplurality of sheath members to laterally expand the sheath memberstoward the soft tissue grafts, thereby urging the soft tissue graftsinto contact with the bone defining the bone tunnel.

In still another aspect of the invention, there is provided a materialfixation system, which comprises a plurality of sheath portions defininga space therebetween, wherein the sheath portions are initially engagedwith one another in an undeployed orientation. An insertion member isinsertable into the space for expanding the sheath portions laterallyoutwardly to a fully deployed orientation in order to urge a soft tissuegraft against an adjacent bone surface. As the sheath portions expandoutwardly to the aforementioned fully deployed orientation, they becomedetached from one another.

In yet another aspect of the invention, there is disclosed a method ofmaking an orthopedic repair by fixing a soft tissue graft to bone. Thedisclosed method comprises a step of creating a tunnel within a desiredbone site, wherein the tunnel extends through a first bone member andcomprises a blind hole in a second bone member. A soft tissue graft isplaced on an implant. The implant is secured within the blind hole, suchthat a plurality of ends of the soft tissue graft extend from theimplant and substantially entirely through the tunnel in the first bonemember. A second implant is then slid along the soft tissue graft endsinto the tunnel in the first bone member, to a predetermined location.The second implant is then expanded outwardly to compress the softtissue graft ends against the bony wall of the bone tunnel.

The invention, together with additional features and advantages thereof,may best be understood by reference to the following description takenin conjunction with the accompanying illustrative drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of the femur and tibia of a patient's leg;

FIG. 2 is a view similar to FIG. 1, showing the use of a drill bit tomake an access tunnel in the femur; and a corresponding blind hole inthe tibia;

FIG. 3 is a view similar to FIGS. 1 and 2 showing the femur and tibiaafter the drilling step has been completed;

FIG. 4 is a view similar to FIGS. 1-3, after a femoral anchor has beeninstalled into the femur access hole, illustrating graft tendon bundlesextend from the femoral anchor through the tibia access tunnel;

FIG. 5 is a view showing a soft tissue graft pre-loaded onto a femoralimplant for use in a graft procedure performed in accordance with theprinciples of the present invention;

FIG. 6 is a view showing the femoral implant being inserted into thefemoral socket and deployed;

FIG. 7 is a view showing the femoral implant inserted being disengagedfrom the deployed femoral implant;

FIG. 8 is an isometric view of an embodiment of a tibial implantconstructed in accordance with the principles of the present invention;

FIG. 9 is a perspective view of a screw portion of the tibial implant ofFIG. 8;

FIG. 10 is a cross-sectional view of the screw portion of FIG. 9;

FIG. 11 is a driver used to deploy the tibial implant of the presentinvention;

FIG. 12 is a perspective view of an assembled tibial implant accordingto the present invention;

FIG. 13 is a perspective view of a disassembled tibial implant accordingto the present invention;

FIG. 14 is a perspective view of an exterior surface of one tibialsheath which forms a part of the tibial implant of the presentinvention;

FIG. 15 is a perspective view of an interior surface of the sheath ofFIG. 14;

FIG. 16 is a perspective view of an assembled tibial sheath according tothe present invention, shown from a first side thereof;

FIG. 17 is a perspective view of the sheath of FIG. 16 shown from asecond side thereof;

FIG. 18 is a top view of the sheath of the present invention;

FIGS. 19-21 show the undeployed tibial implant in the tibia;

FIG. 22 shows the undeployed tibial implant;

FIG. 23 shows the undeployed screw and sheath combination;

FIG. 24 shows the tibial implant as it is in the process of beingdeployed;

FIG. 25 shows the screw rotated to cause the sheaths to start to deployand rotate on their hinges as shown in FIG. 24;

FIG. 26 shows the fully deployed tibial implant;

FIG. 27 shows the fully inserted screw, with the sheaths separated andfully deployed, as shown in FIG. 26;

FIG. 28 is a view showing the fully deployed implant in the tibia;

FIG. 29 is a table showing measured pull out forces for an implant ofthe present invention, compared with the much lower pull out forcesmeasured in a state of the art prior art tibial implant;

FIG. 30 is a perspective view showing a modified embodiment of a sheathwhich forms a part of a tibial anchor device constructed in accordancewith another embodiment of the present invention;

FIG. 31 is a perspective view of an anchor portion of the tibial anchordevice of FIG. 30;

FIG. 32 is a perspective view of a screw of the tibial anchor device ofFIGS. 30 and 31;

FIG. 33 is a perspective view of the opposing side of the sheath shownin FIG. 30;

FIG. 34 is a perspective view of an opposing side of the anchor portionof FIG. 31;

FIG. 35 is view similar to FIGS. 1-4, with portions of the bone removedin order to show the tibial anchor device of FIGS. 30-34, wherein thetendon bundles have been pulled through the sheaths of the anchordevice;

FIG. 36 is a view similar to FIG. 35 wherein the sheaths and anchor havebeen slid up along the tendons into the hole until the anchor bottomsout against an angular surface within the hole;

FIG. 37 is a view similar to FIG. 36, wherein tension has been appliedto the tendons and the screw of FIG. 32 has been inserted into theanchor;

FIG. 38 is a view similar to FIG. 37, wherein the screw has beentightened until it bottoms out against the anchor;

FIG. 39 is a view similar to FIG. 38 wherein the tendon bundles havebeen trimmed flush with the face of the anchor;

FIG. 40 is a view similar to FIG. 39, except that the removed portionsof the bone have been restored in order to shown the patient's kneeafter the inventive repair procedure has been completed;

FIG. 41 is a perspective view showing a right anchor portion of anotherembodiment of a tibial anchor device constructed in accordance with theprinciples of the present invention;

FIG. 42 is a perspective view similar to FIG. 41 showing a left anchorportion of the embodiment of the tibial anchor device of FIG. 41;

FIG. 43 is a view of a screw retention cup of the tibial anchor deviceof FIG. 41;

FIG. 44 is a perspective view of a screw for use with the tibial anchordevice of FIG. 41;

FIG. 45 is a perspective view similar to FIG. 41 of the opposing side ofthe right anchor portion;

FIG. 46 is a perspective view similar to FIG. 42 of the opposing side ofthe left anchor portion;

FIG. 47 is a view similar to FIG. 43 of the opposing side of the screwretention cup;

FIG. 48 is a view of a patient's femur and tibia, with portions of thebone removed for ready visualization, showing the tibial anchor of FIGS.41-47 being installed, by pulling tendon bundles through the left andright anchors;

FIG. 49 is a view similar to FIG. 48, wherein the anchor portions areslid up the tendons into the bone hole until the anchor bottoms outagainst an angular surface in the hole;

FIG. 50 is a view similar to FIG. 49, wherein the tendons have beentensioned, and the screw and retainer cup tightened;

FIG. 51 is a view similar to FIG. 50, wherein the tendon bundles havebeen trimmed flush with the face of the anchor;

FIG. 52 is a view similar to FIG. 51, except that the removed portionsof the bone have been restored in order to shown the patient's kneeafter the inventive repair procedure has been completed;

FIG. 53 is a perspective view of a tibial anchor device similar to thatshown in FIGS. 41-47, in an assembled configuration;

FIG. 54 is another view of the anchor device of FIG. 53;

FIG. 55 is still another view of the anchor device of FIGS. 53 and 54;

FIG. 56 is yet another view of the anchor device of FIGS. 53-55;

FIG. 57 is a view of the anchor device of FIG. 54-56, wherein some ofthe anchor portions have been removed for visibility;

FIG. 58 is a perspective view of yet another tibial anchor embodiment inaccordance with the principles of the present invention;

FIG. 59 is another view of the embodiment of FIG. 58; and

FIG. 60 is still another view of the embodiment of FIGS. 58-59.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now more particularly to the drawings, procedures andanchoring devices for repairing a patient's knee, by securing a graft ofsoft tissue therein, connected between the patient's femur and tibia,are illustrated. There is shown in FIG. 1 a view of a femur 10 and atibia 12 of a patient's knee. FIG. 2 illustrates the same kneestructure, wherein a drill bit 14 is utilized to drill a tunnel in thetibia 12, and a blind hole corresponding to the tunnel in the femur 10.The tibial tunnel 16 and femur blind hole 18 are shown in FIG. 3.

As shown in FIG. 5, a tendon bundle 20 is pre-loaded onto a femoralimplant 22. In a preferred embodiment, the tendon bundle 20 is comprisedof a soft tissue graft comprising a portion of a hamstring (such aspre-harvested semitendinosus and gracilis grafts), but any soft tissuemay be used. Details of a presently preferred femoral implant aredisclosed in co-pending provisional patent application Ser. No.60/854,178, which has already been expressly incorporated herein byreference. However, the invention may be utilized with any suitablefemoral implant.

In FIG. 6, a femoral implant inserter 24 is utilized to insert thefemoral implant into the femoral socket, wherein it is deployed.Following this, as shown in FIG. 7, the femoral implant inserter 24 isdisengaged from the deployed implant 22, and withdrawn.

In FIG. 4, the femoral anchor (not shown) has already been inserted intothe femur blind hole 18 for securing the tendon bundle 20 therein, asshown. As is illustrated, the tendon bundles 20 extend from the femoralanchor in the femur hole 18 down through the tibial tunnel 16.

Referring now to FIGS. 8-10 and 12-18, there is shown a first, andpresently preferred, embodiment of a tibial implant 26 constructed inaccordance with the principles of the present invention. As shown inFIG. 8, the implant 26 comprises a tapered screw 28 and two sheathportions, or halves 30. The two sheath halves 30 are preferably mirrorimages of one another.

The tapered screw 28, shown particularly in FIGS. 9 and 10, has severalkey features. The tapered design, tapering from a relative wide proximalend 32 to a relatively narrow distal end 34, distributes the pressurebetween the tendon and the sheath halves 30 throughout the length of thescrew 28, increasing the pull out force of the system. The screw has aneasy start feature 36, which comprises a cut-out that allows the tip ofthe screw to fit between the sheath halves 30. With the tip between thesheaths, a thread start 38 (FIG. 10) easily engages thread 40 on thescrew with an internal thread 41 of the sheath (FIG. 15) as the screw isrotated clockwise. This minimizes the force required to start the screwby reducing the distance the sheath halves 30 must be spread apart inorder to start the screw. This feature also prevents the user fromneeding to dilate the hole between the tendon bundles. A tapered hex 42(FIG. 10) engages with a driver 44 (FIG. 11) in order to transmit thetorque required in order to deploy the screw. A bullnose screw head 46at the proximal end 32 of the screw 28 leaves a smooth completed repair.

The sheath halves 30 have many key features as well. It is first notedthat having two sheath halves 30 allows for the use of either a doubleor a single tendon bundle loop 20. There is no need to separate fourseparate ends of a double tendon bundle loop into four separatequadrants. With a double bundle loop, the implant has two free ends oneither side of the sheath assembly. With a single bundle loop, one freeend is in place on either side of the sheath assembly. The internalthread 41 (FIG. 15) on each sheath half 30 prevents the screw frombacking out of the sheath assembly during and after deployment. Theinterlocking threads 40, 41 between the screw and the sheaths allow thescrew to be pulled between the sheath halves 30, thus providing easierdeployment. Retaining ribs 48 provide small areas of higher forcebetween the implant and the tendon, thereby increasing the pull outforce of the system.

A cortical hook 50 functions to grab the hard cortical bone of thetibia, which assists in keeping the implant in place during loading andalso increases the pull out force of the system. Each sheath half 30comprises a hinge 52 and a hinge slot 54. The hinge 52 on one sheathhalf 30 is placed in the hinge slot 54 of the opposing sheath half 30.This feature permits the sheath to consistently open up in onedirection, as shown in FIGS. 22, 24, and 26, thus providing a repeatabledeployment mode. One sheath half 30 has two snap posts 56, and theopposing sheath half 30 has a snap hole 58. These features keep thesheath halves 30 from opening prematurely. A screw ramp 60 (FIG. 18)allows for the tip of the sheath to provide compression between thetendon and the bone at the aperture of the tibial tunnel. A bullnosesheath tip 62 provides for a smooth transition between the implantsystem and the exit of the tibial tunnel. This reduces any stressconcentrations that could sever the tendon bundle 20.

Another feature that reduces stress concentrations at the tip of thesheath halves 30 are flex grooves 64. These grooves 64 allow the sheathhalves 30 to flex and form around the tip of the screw 28.

Now with reference to FIGS. 19-28, the deployment of the implant 26 willbe described. The sheath halves 30 of the tibial implant 26 are disposedbetween the tendon bundles 20 in the tibial tunnel 16, which extendproximally through the tibial tunnel 16 from the femoral implant. Thesheath halves 30 are advanced distally through the tunnel 16 until thecortical hook 50 is flush with the cortical surface of the tibia. Thehook is aligned to the top of the tibial tunnel. The graft is thentensioned by pulling the tendons 20 taut, using manual traction,tensioning pulleys, or other suitable means. Again, it is noted that theprimary objective with respect to the tibial anchoring solution is toensure that good aperture fixation is achieved, and to ensure thatcancellous bone fixation is not entirely relied upon. Some type ofcortical fixation or backup is required to ensure a good and permanentresult.

The screw 28 is then placed on a distal end 66 of the hex driver 44until it is fully seated. Next, the screw 28 is placed with the flat ofthe easy start feature 36 parallel with the midplane of the sheathhalves 30. With a force applied in a direction axial to the tibialtunnel, the screw is pushed distally between the sheaths. The implant26, in its undeployed state, is shown in FIGS. 22 and 23.

While the axial force is being applied, and the easy start feature 36 isplaced between the sheaths, the screw is rotated in a clockwisedirection. This further separates the sheath halves 30 and presses thetendons 20 to the wall of the tibial tunnel 16. The hinges 52, 54 alongthe same edge as the cortical hook are used to encourage the sheathhalves to open in one direction, as shown in FIGS. 24 and 25. The screw28 is rotated until it is fully seated when the bullnose screw head 46is flush with the cortical surface of the tibia.

FIGS. 26 and 27 show the screw in a fully inserted state, with thesheath halves 30 separated and fully deployed. In this state, the sheathhalves 30 push the tendons 20 outwardly, into contact with the tibialtunnel walls. The fully deployed implant in the tibia is shown in FIG.28.

As shown in FIG. 29, verification testing of the embodiment shown inFIG. 28 was completed by the inventors, relative to a prior art devicewhich is presently considered to be state of the art. As can be seenfrom the table, the pull out forces for the inventive implant weresignificantly higher than those for the prior art device. The averagepull out force for the inventive device for bovine bone was 1165.2 N, asopposed to 532.7 N for the prior art device.

Now with reference to FIGS. 30-34, various components of anotherembodiment of a tibial sheath anchor are illustrated. In FIGS. 30 and33, there is shown a sheath half 30 from two opposing sides thereof. Ananchor 68 is shown in FIGS. 31 and 34, and comprises a pair of legs 70and a disk 72. A screw 28 is provided for actuating the anchor from anundeployed to a deployed configuration for securing the anchor andassociated tendon bundle in place with respect to adjacent bone.

Referring now to FIG. 35, the patient's femur 10 and tibia 12 are shownwherein a sheath anchor 74 is assembled and disposed for insertion intothe tibial tunnel 16. In accordance with the inventive procedure, thetendon bundles 20 are pulled through the sheath halves 30, as shown,with portions of each sheath half serving to retain the tendon bundlesin place adjacent to the and along the sheaths. In particular, in theillustrated embodiment, tendon loops 76 on each sheath half 30 areformed so that the tendon bundles slide lengthwise along the sheath half30 beneath the loops 76 so that the loops perform a retention function.The anchor 74 and its legs 70 are placed between the sheath halves 30 sothat square tabs 78 on the anchor legs 70 (FIG. 31) are aligned withreceptacle notches 36 on the rear of the sheath half 30 (FIG. 33). Thescrew taper on the rear of the sheath half 30 is oriented toward thejoint 82, between the femur and the tibia.

In FIG. 36, the sheath halves 30 and anchor 68 have been slid up alongthe tendon bundles 20 until the anchor bottoms out against an angularsurface in the hole 16. Then, as shown in FIG. 37, tension is applied tothe tendon bundles 20, and the screw 28 is inserted and tightened withinthe anchor body, using a suitable tool, such as a hex driver. As shownin FIG. 38, the screw 28 should be tightened until it bottoms outagainst the anchor 68, approximately flush with or slightly recessedrelative to the entrance to the tibial tunnel 16. This is important inorder to ensure that there are no protrusions from the tunnels 16 whichcould cause discomfort to the patient or possible later complicationsand wear. An important advantage of the present invention is that thedistal end 84 of the sheath anchor 30, as shown, for example, in FIG.38, is disposed, once the anchor is fully inserted and deployed, so thatit is in close proximity to the distal end (aperture) 86 (FIG. 49) ofthe tibial tunnel 16, at the joint 82. This provides excellent aperturefixation for the tendon bundles 20, in order to minimize wear on thetendon bundles over time due to the “windshield wiper” or “bungee”effects noted above in the Background of the Invention portion of thespecification.

Deployment of the anchor 68 occurs when the screw 28 is inserted intothe anchor body. This insertion action causes the anchor legs 70 tosplay laterally outwardly, thus forcing the sheath halves 30 and tendonbundles 20 against the bony wall forming the tibial tunnel 16. As aresult of this action, the tendon bundles 20 are clamped against thetibial bone 12 by the sheath halves 30.

FIGS. 39 and 40 illustrate the patient's knee joint once the inventiveprocedure has been completed. FIG. 39 shows the joint with portions ofthe bone being removed or transparent so that the entire sheath anchor30 is visible, while FIG. 40 shows the same joint as it would appearnaturally with all bone in place. The final step of the procedure is totrim the protruding ends 88 (FIG. 38) of the tendon bundles 20 so thatthey are flush with the face of the sheath anchor 30.

FIGS. 41-47 illustrate components of a second inventive tibial anchorembodiment, which may be identified as a “cone anchor”. FIGS. 41 and 45illustrate opposing sides of a right anchor portion 90 and FIGS. 42 and46 illustrate opposing sides of a left anchor portion 92. Opposing sidesof a generally conical screw retention cup 94 are shown in FIGS. 43 and47. A screw 28 is shown in FIG. 44. It is noted that, in thisembodiment, all like elements to those shown in previous embodimentswill bear identical reference numerals.

The procedure for utilizing a cone anchor 96 of FIGS. 41-47 (FIG. 48) torepair a patient's joint 82 is initiated in the same manner as for thesheath anchor 30. Thus, as shown in FIGS. 1-4, a femur hole 18 andtibial tunnel 16 are drilled, and a femoral anchor is inserted anddeployed to anchor tendon bundles 20 in place within the femoral hole18, so that the tendon bundles 20 extend downwardly through the tibialtunnel 16, as shown in FIG. 4. The reader is referred to the descriptionabove for further detail regarding this part of the procedure.

Now, as shown in FIG. 48, the tendon bundles 20 are pulled through thecone anchor 96 in order to insert the tibial anchor into the tibialtunnel 16. In this embodiment, the tendon bundles are secured againstthe anchor portions 90 or 92 because they are pulled through tendonloops 76, which are formed in the proximal end of each anchor half 90,92, respectively. Then, as shown in FIG. 49, the anchor 96 is slidupwardly along the tendon bundles 20 until the anchor 96 bottoms outagainst the angular surface in the tibial hole 16, as with the firstembodiment. Again, as in the first embodiment, this positioning willcause the distal end 98 of the anchor 96 to be located in closeproximity to the distal end 86 of the tibial tunnel 16 so that goodaperture fixation will result. Then, as illustrated in FIG. 50, thetendons are appropriately tensioned and the screw 28 is inserted andtightened, together with the retainer cup 94, until seated. This actionof inserting and tightening the screw 28 and screw retainer cup 94 willcause the anchor portions 90, 92 to move laterally outwardly in order toengage the tendon bundles 20 between the anchor portions 90, 92 andadjacent tibial bone, as in the sheath anchor embodiment. FIGS. 51 and52 illustrate the anchor 96 in its fully installed condition, after thetendon ends 88 are trimmed flush and the procedure is otherwisecompleted.

FIGS. 53-57 illustrate, in somewhat greater detail and in an assembledconfiguration, a cone anchor 96 of a type very similar to thatillustrated in the embodiment of FIGS. 41-52. Like elements are denotedby like reference numbers.

A modified tibial anchor embodiment 100 is illustrated in FIGS. 58-60.This embodiment is similar to prior disclosed embodiments to the extentthat there are provided two opposing sheaths having tendon loops 76disposed thereon. A screw 28 and associated screw retention disk or cup94 are also provided. Thus, the basic procedural steps for utilisingthis anchor 100 are similar to those already described in connectionwith the previous disclosed embodiments. What is different about thisembodiment, in particular, is the provision of a distal wedge 101 whichfunctions to provide positive aperture fixation by ensuring that theanchor will be stopped within the tibial tunnel at an appropriate pointduring the insertion step. Pivotable arms 102 connect the anchor body tothe wedge 101, wherein the arms 102 are pivotable outwardly about hinges104. Thus, when it is desired to lock the tibial anchor 100 in placewithin the tibial tunnel, insertion and tightening of the screw 28within the anchor body actuates the arms 102 to pivot outwardlylaterally about the hinges 104, thereby functioning to expand the wedgeand cause positive engagement of the wedge and arms 102 with the tendonbundles and adjacent tibial bone. As in prior embodiments, positivefixation is enhanced by the provision of spikes 106 or other suitablemeans for penetrating the tendon bundles and the bone to lock the tendonbundles and anchor in place.

Accordingly, although an exemplary embodiment of the invention has beenshown and described, it is to be understood that all the terms usedherein are descriptive rather than limiting, and that many changes,modifications, and substitutions may be made by one having ordinaryskill in the art without departing from the spirit and scope of theinvention.

1-55. (canceled)
 56. A method of making an orthopedic repair by fixing asoft tissue graft to bone, comprising: creating a tunnel within adesired bone site, said tunnel extending through a first bone member andcomprising a blind hole in a second bone member; placing a soft tissuegraft on an implant; securing said implant within said blind hole, suchthat a plurality of ends of said soft tissue graft extend from saidimplant and substantially entirely through the tunnel in said first bonemember; sliding a second implant along said soft tissue graft ends intosaid tunnel in the first bone member, to a predetermined location; andexpanding said second implant outwardly to compress the soft tissuegraft ends against the bony wall of said bone tunnel.